The present invention addresses the affordable manufacture of advanced composite automotive structures using repeatable, monitorable, versatile, and production friendly approaches and processes.
The use of advanced composites, defined herein as highly aligned reinforcements of carbon, glass, or aramid fibers in a suitable polymer matrix of either thermoset or thermoplastic resins, is the focus of this invention. The specific intent to use aligned reinforcement is based on the following perception: The modulus of steel is 30,000,000 lbs/in2, whereas the modulus of aluminum is 10,000,000 lbs/in2. The modulus of a typical, higher quality glass epoxy prepreg is around 4,000,000 lbs/in2. While material stiffness can be compensated to some degree via the shaping of the components to enhance structural stability, randomly reinforced composite materials currently being used by the automotive industry have even less stiffness and therefore do not offer the potential for dramatic improvements in structural performance.
For composites to be exploited in the design of an automobile, their unique characteristics must be incorporated into both the design and the production scenario of the vehicle in a way that allows their inherent advantages to be realized.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
In another aspect, the present invention provides methods and techniques for integrating the production demands of higher volume automotive structures with the higher performance available from advanced composite materials, in a way that yields repeatable, affordable performance. The Invention provides processes for continuous, tailored lamination of aligned composite materials in such a way that either pre-formed or pre-consolidated sheets are made available for subsequent infusion molding or stamping processes respectively. The infusion processes are not unlike those already in widespread use such as resin transfer molding (RTM) or vacuum assisted resin transfer molding (VARTM). The stamping process is not unlike what is currently used to stamp steel automotive structures. For either approach, liquid infusion or solid state stamping, component design must be tailored to the processes to achieve performance and cost goals. The concept incorporates aspects of several available technologies including fiber or tape placement, stretch-broken and commingled fiber yarns, binderized pre-forming, heated consolidation, and NC cutting and kitting. The process that is the subject of this invention can be used with either thermoplastic or thermoset matrix resins by manipulating the various options inherent in each process step of the invention.
Advantages to this invention are that it addresses fundamental elements required if a breakthrough in affordable high performance and high volume advanced composite automotive structures are to become a reality. Issues this invention successfully address are: 1) the need for minimal touch labor between part design and near-finished part, 2) highly repeatable, tailorable, versatile, and controllable processes, 3) minimization of scrap materials during fabrication, 4) inline process monitoring and control (to minimize post-inspection and scrapped finished components), 5) delivery of xe2x80x9cadvanced compositexe2x80x9d performance via aligned xe2x80x9ccontinuousxe2x80x9d-like fibrous reinforcement, 6) ability to handle the lay-up of many laminate architectures using the same equipment and switch between lay-ups readily to manage and balance production leveling for a range of model variants etc., and 7) in-line approach to applying other materials and value added functionality such as sound and vibration dampening, paintless coloring and finish, integral trim surfaces, among other benefits.
Accordingly, the present invention is directed to a process and equipment for manufacture of advanced composite structures.
An object of the present invention is to produce large aligned carbon reinforced components that assemble easily.
Another object of the present invention is to improve the speed and efficiency of production every year.
Another object of the present invention is to create a repeatable and consistent process in terms of quality, performance, mass, fit and function.
Another object of the present invention is to eliminate conventional painting.
Another object of the present invention is to balance capital investment with production rate and volume.
Another object of the present invention is to have a logical approach to materials handling and inventory.
Another object of the present invention is to seek a solution that minimizes scrap.
Another object of the present invention is to start with materials as close to raw material forms as possible.
Another object of the present invention is to automate as much as possible.
Another object of the present invention is to maintain a safe, clean and manageable production environment.
Another object of the present invention is to incorporate aligned carbon reinforcement.
Another object of the present invention is to control laminate architecture.
Another object of the present invention is to tailor the component design to the unique aspects of the manufacturing process being considered.
Another object of the present invention is to consider the extremes of using the same laminate, thickness, and material everywhere.
Another object of the present invention is to utilize flexibility in terms of risk, starting materials, and quality achieved.